Master-Slave PWM Regulator Ripple Coupling for Transient Stability
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Solution Overview
Problem
Existing master/slave peak current-mode PWM switching regulators suffer from sub-harmonic recovery to load transient events, output voltage disturbances during dynamic output voltage slewing, and large-signal anomalies due to mismatches between master and slave controller circuits, which are exacerbated by the use of all-ceramic output capacitor filters with small inductance values, leading to performance limitations.
Innovation Solution
The solution involves coupling the ripple resistor current from the slave controller circuit to the master controller circuit, allowing the curvatures of the ripple voltage waveforms in both circuits to be similar, thereby enhancing the frequency response and transient performance by synchronizing the ripple voltage across the switching regulator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If master/slave peak current-mode PWM switching regulators are used, then switching regulation functionality is achieved, but sub-harmonic recovery to load transient events deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the ripple voltage from the slave controller is fed back to the master controller. Specifically, the ripple voltage generated by the slave controller during switching operations is coupled back to the master controller's current mode PWM circuitry. This feedback allows the master controller to sense and respond to load transient events more effectively, improving sub-harmonic recovery by providing real-time information about the slave controller's operating state and enabling coordinated control adjustments.
Solution Approach 2:
The patent introduces an intermediary coupling mechanism between the master and slave controllers. A coupling circuit is employed to transfer the ripple voltage signal from the slave controller to the master controller without directly connecting the two control circuits. This intermediary approach allows information exchange for improving transient response while maintaining the independence and simplicity of each controller's internal structure, thus not increasing overall device complexity.
2Reliability
If master/slave peak current-mode PWM switching regulators are used, then switching regulation functionality is achieved, but output voltage disturbances during dynamic output voltage slewing occur
Solution Approach 1:
The ripple voltage feedback from the slave controller to the master controller provides real-time information about the switching state and load conditions. During dynamic output voltage slewing, this feedback enables the master controller to detect voltage disturbances and adjust its control signals accordingly, thereby stabilizing the output voltage. The feedback mechanism allows coordinated control actions between master and slave controllers to mitigate output voltage disturbances without requiring complex additional circuitry.
3Reliability
If master/slave peak current-mode PWM switching regulators are used, then switching regulation functionality is achieved, but large-signal anomalies due to mismatches between master and slave controller circuits occur
Solution Approach 1:
The patent employs ripple voltage feedback to continuously monitor the slave controller's operation and provide this information to the master controller. This feedback mechanism enables the master controller to detect and correct mismatches between master and slave controller circuits by adjusting its control signals based on the slave's actual performance. The synchronization is achieved through this closed-loop information exchange rather than through complex matching circuitry, maintaining simplicity while improving reliability.
4Volume of moving object
If all-ceramic output capacitor filters with small inductance values are used, then filter size is reduced, but performance limitations are exacerbated
Solution Approach 1:
The ripple voltage feedback mechanism compensates for the performance limitations of compact all-ceramic output capacitor filters with small inductance values. By providing real-time information about the slave controller's switching state and load conditions to the master controller, the feedback enables coordinated control actions that maintain stable operation and improve transient response performance. This allows the use of smaller filters without sacrificing reliability, as the control system actively compensates for the reduced filtering capability.
Data Source
AI summary
A system, switching regulators, and methods of control for enhanced peak current-mode PWM switching regulators are disclosed. For example, a switching regulator is disclosed, which includes a master controller circuit and a slave controller circuit coupled to the master controller circuit, wherein the slave controller circuit is configured to generate a ripple current at a first ripple node, and a sensor circuit is configured to sense the ripple current at the first ripple node and convey the sensed ripple current to a second ripple node in the master controller circuit. In some implementations, the switching regulator is part of a power subsystem formed on one or more semiconductor ICs, wafers, chips or dies.